Here's why:

* Mechanical waves require a medium (like air, water, or a solid) to travel. They are vibrations that transfer energy through the particles of the medium.

* Electromagnetic waves are disturbances in electric and magnetic fields that can propagate through space even without a medium. They are made up of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation.

The classic example is light. Light is a form of electromagnetic radiation and can travel from the Sun to Earth through the vacuum of space.